Zygote of
Silvetia (which was called Pelvetia)
Forty minutes after fertilization, the zygote begins cell wall synthesis
and two hours after fertilization, the first deposition of alginic
acid occurs. Twelve hours later, the zygote forms a primary, unicellular
rhizoid from one side which faces away from light while the rest of
the zygote becomes the embryo. S. compressa actually has delayed
rhizoid development so it first secures the zygote with a specialized
mesochiton. It then divides to form a minute cylindrical plant with
an apical cell with trichothallic growth, producing hairs above and
below the thallus. Eventually, the apical cell ceases production of
hair cells and becomes 3-sided and later 4-sided. Only after the apical
cell is initiated will the thallus assume the mature flattened shape.
Forty minutes after fertilization, the zygote begins cell wall synthesis and two hours after fertilization, the first deposition of alginic acid occurs. Twelve hours later, the zygote forms a primary, unicellular rhizoid from one side which faces away from light while the rest of the zygote becomes the embryo. S. compressa actually has delayed rhizoid development so it first secures the zygote with a specialized mesochiton. It then divides to form a minute cylindrical plant with an apical cell with trichothallic growth, producing hairs above and below the thallus. Eventually, the apical cell ceases production of hair cells and becomes 3-sided and later 4-sided. Only after the apical cell is initiated will the thallus assume the mature flattened shape.
© 1996 R. H. Lin